Dam foes say time is right to seek changes

By Chiu Yu-Tzu / STAFF REPORTER

In the wake of the recent Taoyuan County water crisis, the Water Resources Agency's (WRA) top priority is to dredge Shihmen Dam, one of northern Taiwan's major reservoirs, to tackle turbidity problems and lengthen the reservoir's lifespan.

Environmental groups say this also is a good time to consider alternatives to dams, which played a large role in the water crisis.

The long suspension of water services in Taoyuan was attributed to the abnormally high turbidity of untreated water in the nation's third largest reservoir.

Late last month and into this month, heavy rains brought by Typhoon Aere washed more than 20 million m3of silt, mud, driftwood and other debris into the reservoir.

That estimate was about 14 times the expected annual silt deposits for the reservoir, officials said, and is equal to 35.8 percent of all the silt that has accumulated in the past 41 years.

The Taoyuan water purification plant was unable to function properly with turbid water, so nearly a million south Taoyuan residents were left without water for more than two weeks.

The agency said the Shihmen Dam reservoir could lose seven years of its useful lifespan if silt continues to accumulate at such rates.

So WRA officials said their top priority is to dredge the reservoir and discharge silt before winter, when much less rainfall is expected than in summer.

However, dam opponents argue that alternatives to dams should be sought because the reservoir, built originally for irrigation, power generation and water supply, has caused major problems.

According to Chung Yi-ting (鍾怡婷) of the Meinung People's Association (美濃愛鄉協進會), an environmental group which has opposed dams since the early 1990s, in the US and some European countries, aging dams are being dismantled or decommissioned due to concerns about structural safety, siltation, ecological damage and other factors.

"If Western countries have the confidence to review the situation they are in, why not Taiwan?" Chung said in an interview with the Taipei Times.

WRA statistics show that siltation has robbed about 40 major reservoirs of 12 percent of their total effective storage capacity. Also urgently needed, Chung said, is a review of other dam-related issues such as poor design, inefficient operation, possible ecological catastrophes and changing societal needs.

In mid-October more than 20 environmental groups and research centers will sponsor the International Conference on Dam Alternatives to discuss critical water issues.

Chung, the event's coordinator, said conservationists from the Japan, other Asian countries and the US would review water policies and share river conservation ideas at the three-day conference.

The nation needs these new ideas to manage its water resources, he said.

"For example, abnormal rainfall caused by global climate changes has been observed in Taiwan. However, greenhouse gas emission from dams remains rarely considered by the government," Chung said.

Citing research from the International Rivers Network, a California-based organization supporting local communities working to protect their rivers and watersheds, Chung said that some Western researchers believe that releases of dissolved methane from water discharged from dams may prove to be the largest component of the warming impact of tropical hydropower.